Damped valve controller

ABSTRACT

A damping assembly for an engine valve, the engine valve being an intake/exhaust valve, the engine valve admitting/exhausting a fluid mixture into/from a combustion chamber of an internal combustion engine includes damping apparatus having a damping chamber being selectively in fluid communication with a source of pressurized actuating fluid and being in fluid communication with a substantially ambient actuating fluid reservoir and being operably coupled to the engine valve. The chamber is floodable with a volume of actuating fluid, venting of actuating fluid from the chamber being selectively restricted. The restriction imparts a force to the engine valve acting to moderate engine valve landing speed during a closing stroke of the engine valve. A method of control is further included.

RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of U.S. patentapplication Ser. No. 10/072,490, filed Feb. 5, 2002, and acontinuation-in-part of U.S. patent application Ser. No. 10/105,482,filed Mar. 25, 2002, both being incorporated herein by reference.

TECHNICAL FIELD

[0002] The present application relates to internal combustion enginevalve control. More particularly, the present application relates tocamless control of engine intake/exhaust valves.

BACKGROUND AND PRIOR ART

[0003] There is a need in the industry for increased control of internalcombustion operating parameters in order to provide for efficient andpowerful operation, while at the same time, minimizing the emissions ofnoxious byproducts of combustion and minimizing noise emissions. Theissue of noise emissions is particularly a problem with combustionignition engines, and most particularly, a problem at idle speedconditions and during cold start-up. A source of the noise emissions isthe landing impact of engine air (intake/exhaust) valves. A harshlanding impact also adversely affects the durability of valve traincomponents.

SUMMARY OF THE INVENTION

[0004] The present invention substantially meets the needs of theindustry. Control of the engine valve landing speed is achieved by adamping device that modulates the velocity of the engine valve as theengine valve approaches the closed condition, in one embodiment andmodulates landing both in the valve closing and opening conditions inanother embodiment.

[0005] The present invention is a damping assembly for an engine valve,the engine valve being an intake/exhaust valve, the engine valveadmitting/exhausting a fluid mixture into/from a combustion chamber ofan internal combustion engine includes damping apparatus having adamping chamber being selectively in fluid communication with a sourceof pressurized actuating fluid and being in fluid communication with asubstantially ambient actuating fluid reservoir and being operablycoupled to the engine valve. The chamber is floodable with a volume ofactuating fluid, venting of actuating fluid from the chamber beingselectively restricted. The restriction imparts a force to the enginevalve acting to moderate engine valve landing speed during a closingstroke of the engine valve. The present invention is further a method ofcontrol.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a sectional view of a valve actuation device of theinvention of the parent application;

[0007]FIG. 2 is a sectional view of the valve actuation device of FIG. 1integrated with the dual control valve of the parent invention; and

[0008]FIG. 3 is a graphic representation of the control strategy for thevalve actuation device of FIGS. 1 and 2;

[0009]FIG. 4 is a partially sectioned schematic representation of theclosing damping assembly of the present invention integrated with thedual control valve of the parent invention;

[0010]FIG. 5 is an enlarged sectioned schematic representation of thedamping assembly of the present invention;

[0011]FIG. 6 is a sectioned schematic representation of the dampingassembly of the present invention having frames A-D depicting sequentialoperating conditions;

[0012]FIG. 7 is a partially sectioned schematic representation of theopening damping assembly of the present invention, having frames A-Cdepicting sequential operating conditions;

[0013]FIG. 8 is a partially sectioned schematic representation of afurther embodiment of the opening damping assembly of the presentinvention, having frames A-C depicting sequential operating conditions;and

[0014]FIG. 9 is a graphic representation of the control strategy for thedamping assembly of FIGS. 4-8.

DETAILED DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 shows a dual control valve 500 in application on a camlessengine. More detail of the structure and operation of an exemplary dualcontrol valve 500 may be had with reference to the parent application.FIG. 2 illustrates the structure of valve actuator 600 in greatestdetail. FIG. 3 illustrates the relationship between the control valve500 and the valve actuator 600.

[0016] The valve actuator 600 contains major components of boost piston620, drive piston 622 and return piston 618. Pressure in the boostpiston control chamber 626 is controlled by the half spool valve (CV1 ofFIGS. 4-8) 504. When the half spool control valve 504 is turned on (seeFIG. 3), the boost piston chamber 626 of the boost piston 620 isconnected to the rail pressure from rail 542, the actuating fluidpassing through the half spool valve 504 and passage 624 to the boostpiston chamber 626. The boost surface 628 of the boost piston 620 has arelatively large area and it provides sufficient downward force on theengine valve 604 to overcome the incylinder combustion pressure actingin opposition on the valve face 605. The boost piston 620 has ofrelatively limited stroke 627. Preferably, the stroke 627 is on theorder of about 2 mm.

[0017] It is desirable that the stroke 627 of the boost piston 620 beless than the cylinder head to combustion piston clearance at TDC toavoid inadvertent collision of valve 604 and the combustion piston. Thestroke limit 627 is realized by a hard stop 629 to the boost piston 620travel. Due to its limited stroke 627, boost piston 620 can be opened atany time without regard to combustion piston disposition relative to thecylinder head without hitting the combustion piston. The responsibilityof the boost piston 620 is to crack open the engine valve 604 at arelatively high in-cylinder pressure condition and hold the valve 604 atthe stroke limiter on the stop 629 for a selected period of time. Thisfeature is referred to as engine valve overlapping noted on FIG. 3 asvalve overlap.

[0018] The drive piston 622 positioning control pressure charge iscontrolled by the balance spool valve 502 (CV2 of FIGS. 4-8). Balancespool valve 502 selectively ports high pressure actuating fluid fromrail 542 to the drive piston 622 via passage 625 or vents actuatingfluid therefrom via vents 537. The drive piston 622 and boost piston 620are in mechanical contact (the distal end 631 of the boost shank 630bearing on the drive area 638 of the drive piston 622) when the enginevalve 604 opening is less than or equal to the boost stroke limit 627.

[0019] When engine valve 604 travel is greater than the boost limit (thestroke 627), the drive piston 622 and boost piston 620 are mechanicallyseparated (the distal end 631 of the boost shank 630 is no longerbearing on the drive area 638 of the drive piston 622) and the drivepiston 622 is responsible for fully opening (see full open position ofFIG. 3) the engine valve 604 without the assistance of the boost piston620. The drive piston 622 and return piston 618 are always in mechanicalcontact with the engine valve 604 and the contact area beneath theretainer 608 is vented to ambient pressure by the vent 642.

[0020] The drive piston 622 is responsible for fully opening the enginevalve 604 by overcoming all biased forces, including the force exertedby the return spring 610, the force exerted by the return piston 618,and any in-cylinder forces acting on the surface of valve 604. The drivepiston 622 has the capability to push the valve 604 to the full valve(open) lift position and stay at that position for the entire durationof valve 604 opening. This is effected by appropriately sizing the drivearea 638 to generate adequate force by the pressure to be exertedthereon by the actuating fluid ported from CV2 502. The drive piston 622may be used sequentially or in conjunction with the boost piston 620during the valve 604 actuation as desired to meet the valve 604 openingneeds since the pistons 620, 622 are independently controlled by CV1502, CV2 604, respectively. The drive piston 622 is capable of travelingthe full valve lift distance of valve 604 for any given actuationpressure (pressure in the rail 542) and stops when full travel isreached. How fast drive piston 622 moves is largely a function of theactuation pressure in the rail 542.

[0021] The return piston 618 is operably coupled to the valve springretainer (valve plate) 608 at the upper margin of the return piston 618.The opposed lower margin 619 forms a portion of the return pistoncontrol chamber 640. Chamber 640 is always exposed to actuating fluidpressure from rail 542 during engine operation. The return piston 618 isalways connected to the rail pressure in the rail 542 without anycontrol being exerted on the actuating fluid affecting the return piston618 and accordingly always exerts a closing force on valve 604. Thereturn piston 618 always tends to the push the valve 604 to the closedposition in cooperation with the bias exerted by the return spring 610.The drive area 638 of the drive piston 622 is significantly greater thanthe actuation area 619 of the return piston 618, hence the drive piston622 can always open the valve 604 against the force exerted by thereturn piston 618 acting in cooperation with the bias exerted by thereturn spring 610.

[0022]FIG. 3 illustrates the control strategy of the stepped valvemotion method. Before the combustion piston reaches the top dead center,TDC, position, the half spool valve (CV1) 504 is turned on, portingactuating fluid to the drive the boost piston 620 to its stroke limit627 position on the stop 629. Since the drive piston 620 is inmechanical contact with the boost piston 622 at the home (initial)position, the entire moving mass (boost piston 620, drive piston 622 andthe valve 604) is being pushed the distance of the stroke 627, about 2mm, to the stop 629 and stopped at that position (see position A of FIG.3).

[0023] The combustion piston continues its approach to TDC and passesTDC without hitting the cracked open engine valve 604. As soon as thepiston passes TDC, the balanced spool valve (CV2) 502 is turned on totrigger the drive piston 622 take off. Rail pressure is now incommunication with the drive piston chamber 636 and acting on the drivearea 638. The drive piston 622 mechanically separates from the boostpiston 620 and pushes the engine valve 604 to the full open extent ofits travel (see position B of FIG. 3) by overcoming the biased returnpiston 618, the return spring 610 preload force and some in-cylinderpressure force acting on valve face 605. The engine valve 604 reachesits fuel travel and stops.

[0024] After the desired engine valve opening duration, the balancedspool valve (CV2) 502 is turned off and the drive piston chamber 636 isvented through vents 537. The return piston 618 and the return spring610 then push the engine valve 604 and the drive piston 622 back to the2 mm position (see position C of FIG. 3). Two different situations canhappen at this returning position C.

[0025] In the first situation, the boost piston 620 is still inconnection with the rail pressure through the closed control valve (CV1)504 and the boost piston 620 is still set at its stop 629 at the strokelimit 627. The return piston 618 will carry the engine valve 604 anddrive piston 622 together to hit this distal end 631 of the boost piston620 and will stop against the boost piston 620 due to significant forceacting on the boost piston 620 by the actuating fluid in the boostpiston chamber 626 acting on the boost surface 628. The engine valve 604moving mass now is stopped at the 2 mm lift. After a selected period oftime, the half spool control valve 504 is shifted to the on position andvents the boost piston chamber 626 through the vent 539. The returnpiston 618 then pushes the entire mass back to the home position withvery small landing velocity (see position D of FIG. 8). The very limitedtravel distance of the stroke 627 prevents developing high landingvelocity before the mass is stopped. This method is very beneficialunder high return speed when the engine is operating at relatively highRPM to minimize the valve 604 returning impact.

[0026] The second situation is as noted below. The boost piston chamber626 is vented before the engine valve 604 returns to the 2 mm position.This occurs by the half spool control valve (CV1) 504 being shifted tothe vent position and venting the boost piston chamber 626 through thevent 539. The returning drive piston 622 will then hit the distal end631 of the boost piston. The entire moving mass is then increased byhaving to carry the boost piston 620, as well as the drive piston 622and the valve 604 and this results in an increased system inertia. Theentire moving mass accordingly slows down. The reduced return velocityacts to advantageously reduce the impact of the valve 604 on thecylinder head seat 612. This situation is advantageously used in lowengine speed conditions and other low rail pressure conditions when thereturning speed is relatively low.

[0027] The dual control valve 500 of the present invention having twocontrol valves 502, 504 assures the safety of the valving mechanism 600.The combustion piston to the engine valve 604 collision condition isavoided and return forces of the valve 604 are better controlled.

[0028] Enhanced control of the return forces of the valve 604 isachieved with the return damping assembly of the present invention,depicted generally at 700 in FIGS. 4-6. The return damping assembly 700of the present invention is depicted in FIGS. 4-6, with the structure ofthe return damping assembly 700 being depicted primarily in FIGS. 4 and5 and operation of the return damping assembly 700 being depicted inFIG. 6 in sequential frames A-D. Incorporation of the return dampingassembly 700 includes some modifications to the structure of the boostpiston 620 and drive piston 622 as described above with reference toFIGS. 1-3.

[0029] The boost piston 620 has an axial bore 702 defined therein. Theupper margin of the axial bore 702 is sealed by a plug 704 that isthreaded into the boost piston 620. The axial bore 702 defines in part adamping ball chamber 706 and a depending drive piston cylinder 708. Thediameter of the damping ball chamber 706 is greater than that of thedrive piston cylinder 708.

[0030] The damping ball chamber 706 is intersected by a chamber crossdrilling 710. Likewise, the drive piston cylinder 708 is intersected bya piston cross drilling 712. Both the chamber cross drilling 710 and thepiston cross drilling 712 are in fluid communication with an annulus714. The annulus 714 is in fluid communication with CV2 502 viapassageway 625. As will be seen, pressure in the annulus 714 iscontrolled by CV2 502.

[0031] The damping ball chamber 706 is defined by a ball stop 716,comprising the lower margin of the plug 704, in cooperation with acylinder wall 718 and a step comprising a ball seat 720 that is radiallydisposed with respect to the drive piston cylinder 708.

[0032] The drive piston 622 utilized with the return damping assembly700 comprises a cylindrical piston body 722. The piston body 722 has alower margin 724 that bears on the upper margin of the return springretainer 608 of the valve 604. The piston body 722 has a ring shaped,planar upper margin 726. A lead piece 728 having a lesser diameter thanthe piston body 722 projects upward from the upper margin 726. The leadpiece 728 has a lead upper margin 730.

[0033] The return damping assembly 700 includes a damping ball 732disposed within the damping ball chamber 706. The damping ball 732 has alesser diameter than the diameter of the cylinder wall 718 of dampingball chamber 706. Accordingly, the damping ball 732 is free to floatwithin the damping ball chamber 706. The distance between the ball stop716 and the lower margin 740 of the chamber cross drilling 710 is lessthan the radius of the damping ball 732. A damping ball clearance 734 isdefined between the circumference of the damping ball 732 and thecylinder wall 718 of the damping ball chamber 706. The damping ballclearance 734 is generally the area defined between the circumference ofthe damping ball 732 and the circumference of the cylinder wall 718 ofthe damping ball chamber 706. Accordingly, the damping ball clearance734 is always the same even if the damping ball 732 floats and isbearing on the ball stop 716.

[0034] Actuating fluid flow past the damping ball 732 must transit thedamping ball clearance 734 under all conditions. As will be noted below,the damping ball clearance 734 is a critical dimension with respect tooperation of the return damping assembly 700.

[0035] The damping stroke 736 is defined between the ball seat 720 andthe upper margin 738 of the piston cross drilling 712. The dampingstroke 736 is adjustable by varying the aforementioned distance duringformation operations of the boost piston 620 by disposing the pistoncross drilling 712 closer to or more distant from the ball seat 720.

[0036]FIG. 6 depicts the operation of the return damping assembly 700.As noted in FIG. 9, return damping as effected by the return dampingassembly 700 occurs on the closing stroke of the valve 604.

[0037] Operation of the return damping assembly 700 will first bedescribed during opening of the valve 604. It should noted that nodamping is effected by the return damping assembly 700 during theopening stroke of the valve 604. During the opening stroke of the valve604, CV2 502 is shifted to the open disposition porting high pressureactuating fluid from the rail 542 through the passageway 625 to theannulus 714. Referring to A of FIG. 6, high pressure actuating fluidflows through the chamber cross drilling 710 and floods the upperportion (the portion above the damping ball 732) of the damping ballchamber 706. The pressure of the actuating fluid generates a downwardforce on the upper hemisphere of the damping ball 732. This force istransmitted to the lead upper margin 730 and accordingly then to theboost piston 620 and the valve 604, tending to drive the boost piston720 and valve 604 in a downward, opening stroke. A certain portion ofthe high pressure actuating fluid transits the damping ball clearance734 and enters the portion of the damping ball chamber 706 that isbeneath the damping ball 732. The pressure of the actuating fluidbeneath the damping ball 732 acts on the upper margin 726 of the pistonbody 722, thereby generating a downward force on the boost piston 620that is additive to the aforementioned force generated on the upperhemisphere of the damping ball 732. The damping ball 732, boost piston620, and valve 604 translate downward as indicated in frame B of FIG. 6.

[0038] Referring to frame C of FIG. 6, the damping ball 732 is seated onthe ball seat 720. At this point, the piston cross drilling 712 is influid communication with the drive piston cylinder 708 and high pressureactuating fluid from annulus 714 bears on the upper margin 726 of theboost piston 720, driving the boost piston 620 and the valve 604 furtheropen as indicated in frame D. No damping is effected by the returndamping assembly 700 during the opening stroke of valve 604.

[0039] The return damping stroke of the return damping assembly 700proceeds in the opposite sequence to that described above with referenceto the opening stroke. The sequence is from frame D to A of FIG. 6. Toinitiate the return stroke, CV2 502 shifts from the open disposition tothe venting disposition in which high pressure actuating fluid from rail542 is sealed off and the components serviced by CV2 502 are vented toambient via vent 537. Accordingly, the pressure of the actuating fluidin the damping ball chamber 706 and the drive piston cylinder 708 dropsquickly to ambient. It should be noted that the volumes defined by thedamping ball chamber 706 and the drive piston cylinder 708 are stillflooded with actuating fluid, but at ambient pressure.

[0040] The valve 604 commences its return, closing stroke as describedabove with reference to FIGS. 1-3. The closing stroke proceeds from thedepiction from frame D to the depiction of frame C with the actuatingfluid in the drive piston cylinder 708 being expelled through CV2 502 toambient. There is relatively little resistance imposed on boost piston620 by the venting of the actuating fluid from the drive piston cylinder708.

[0041] In frame C, lead piece 728 of the boost piston 620 comes intocontact with the seated damping ball 732. Damping or modulation of theclosing velocity of the valves 604 commences once the lead piece 728 isagain in contact with the damping ball 732.

[0042] Upwards translation of the entire mass, comprising the valve 604,boost piston 620, and damping ball 732, is limited by forcing theactuating fluid trapped beneath the damping ball 732 through the dampingball clearance 734 and thence to ambient pressure via the chamber crossdrilling 710, annulus 714, and CV2 502. The force necessary to expel thetrapped actuating fluid is sufficient to slow the closing velocity ofthe valve 604. The area of the damping ball clearance 734 directlyaffects reduction in the landing velocity of the valve 604. If the areaof the damping ball clearance 734 is too restrictive, the valve 604approaches a hydraulic lock condition in which all upward, closingmotion is terminated. If the area of the damping ball clearance 734 istoo great, the landing velocity of the valve 604 is not adequatelydiminished and the impact of the valve spring retainer 608 on lowermargin of the drive piston 622, as depicted in frame A, is too harsh.This harshness adversely affects the durability of the variouscomponents and additionally, contributes significantly to engine noiseemissions, especially during idle operation of a compression combustionengine. With proper damping ball clearance 734, landing velocity of thevalve 604 is modulated as indicated by the dashed line of FIG. 9referring to return damping.

[0043]FIGS. 7 and 8 depict two different embodiments of an openingdamping assembly 800. In both cases the opening damping assembly 800includes a return pin 822 that is translatable in two opposeddirections. When translating upward, the return pin 822 acts to assistthe return or closing stroke of the valve 604. When traveling downward,the last portion of the downward stroke of the return pin 822 acts todampen the opening motion of the valve 604, as noted below.

[0044] With reference to the embodiment of FIG. 7, the opening dampingassembly 800 has three major components: housing 820, the return pin822, and damping ball 824.

[0045] The housing 820 includes a bore 826 defined therein. The bore 826is preferably spaced apart from and parallel to the stem 605 of thevalve 604. The bore 826 is open at the top margin and is blind at thebottom margin. The bore 826 defines a return pin cylinder 828 and adamping chamber 830. The damping chamber 830 has a greater diameter thanthe return pin cylinder 828. Cylinder cross drilling 832 intersects thereturn pin cylinder 828 and is in fluid communication with CV2 502 viathe fluid passageway 625. Likewise, a chamber cross drilling 834 is influid communication with the damping chamber 830. The chamber crossdrilling 834 is in fluid communication with CV2 502 via the fluidpassageway 625. The upper margin of the damping chamber 830 is a ringshaped, planar step comprising a ball stop 836.

[0046] The return pin 822 is an elongate pin that functions as a valveclosing drive piston that acts in cooperation with the bias of the valvespring 610. The return pin 822 has a head 838. The upper margin 840 ofthe head 838 is operably coupled to the underside of the spring retainer608 of the valve 604.

[0047] A shank 842 depends from the head 838 and is translatablydisposed in the return pin cylinder 828. A lead piece 844 has a smallerdiameter than the diameter of the shank 842 and projects downward fromthe shank 842. A ring-shaped actuator surface 846 defines the lowermargin of the shank 842. The lead piece 844 has a lead lower margin 848.

[0048] The damping ball 824 is captured within the damping chamber 830.The damping ball 824 has a damping ball clearance 850 defined betweenthe damping ball 824 and the wall of the damping chamber 830. Thedamping ball clearance 850 has all the characteristics noted above withreference to the damping ball clearance 734.

[0049] The first function of the return pin 822 is to assist the valvespring 610 in closing the valve 604. To that end, referring to frame Cof FIG. 7, CV2 502 is shifted to the open disposition porting highpressure actuating fluid into both the cylinder cross drilling 832 andthe chamber cross drilling 834. Initially, the cylinder cross drilling832 is sealed off by the shank 842 of the return pin 822. High pressureactuating fluid enters the damping chamber 830 and generates an upwarddirected force on the lower hemisphere of the damping ball 824. Thedamping ball 824 bears on the lead lower margin 848 of the lead piece844 and drives the return pin 822 and the valve 604 upward.

[0050] The action of the damping ball 824 in closing the valve 604 isarrested when the damping ball 824 is seated on the ball stop 836. Atthis point, the actuator surface 846 has intersected the cylinder crossdrilling 832 and the high pressure fluid generates an upward directedforce on the actuator surface 846 driving both the return pin 822 andthe valve 604 in the upward return direction.

[0051] Referring to frame A of FIG. 7, as soon as the lower margin 848of the lead piece 844 is also exposed through high pressure actuatingfluid, a force is generated on the lead lower margin 848 that isadditive to the force being generated on the actuator surface 846 toreturn the valve 604 to the closed disposition.

[0052] The opening stroke of the valve 604 commences at frame A of FIG.7. CV2 502 is shifted to the vent disposition, dropping the pressure ofthe actuating fluid in both the return pin cylinder 828 and the dampingchamber 830 to ambient. The downward opening stroke of the valve 604carries with it the return pin 822. As the return pin 822 descends,actuating fluid is expelled from the return pin cylinder 828 through thecylinder cross drilling 832 with essentially no resistance.

[0053] Once the actuator surface 846 descends past the lower margin ofthe cylinder cross drilling 832, the cylinder cross drilling 832 issealed off. Actuating fluid in the damping chamber 830 must be forcedaround the damping ball 824 in the area defined by the damping ballclearance 850. The restriction generated by the damping ball clearance850 slows the downward translation of the return pin 822. This in turnslows the downward, opening velocity of the valve 604, thereby graduallyreducing the landing speed of the valve 604 as the valve 604 achieves itfull open disposition. This gradual reduction in landing speed is notedby the dashed lines depicting opening damping in FIG. 9. The reducedlanding speed necessarily takes additional time for the valve 604 toachieve its full open position, thereby generating the gradual approachto the full open disposition.

[0054] The second embodiment of the opening damping assembly 800 isdepicted in FIG. 8. In the embodiment of FIG. 8, the return pin 822 is acylindrical sleeve that is concentric with the valve stem 605 of thevalve 604. The upper margin 840 of the return pin (sleeve) 822 bears onthe underside of the valve spring retainer 608 of the valve 604.

[0055] The damping chamber 830 is formed at the lower margin of thereturn pin cylinder 828. The ball stop 836 is formed at the inner marginof the chamber cross drilling 834. The ball stop 836 is formed such thatwhen the damping ball 824 is seated on the ball stop 836, as depicted inframe A and B of FIG. 8, an orifice of selected size exists between thedamping ball 824 and through the ball stop 836. Accordingly, when thedamping ball 824 is seated on the ball stop 836, the chamber crossdrilling 834 is fully sealed off with the exception of the area definedby the orifice 852. The orifice 852 is always open for the transmissionof actuating fluid. Actuating fluid is therefore free to escape aroundthe damping ball 824, through the orifice 852 and out the chamber crossdrilling 834 when the damping ball 824 is seated on the ball stop 836.

[0056] Operation of the embodiment of FIG. 8 is similar to operation ofthe embodiment of FIG. 7 described above. The return, closing stroke ofthe valve 604 is initiated by shifting CV2 502 to the open disposition,thereby porting high pressure actuating fluid to both the cylinder crossdrilling 832 and the chamber cross drilling 834. Initially, the cylindercross drilling 832 is sealed off by the return pin (sleeve) 822. Highpressure actuating fluid passes through the chamber cross drilling 834into the damping chamber 830 essentially without restriction as thedamping ball 824 is forced out of the path of the high pressureactuating fluid. The high pressure actuating fluid generates a force onthe actuator surface 846 driving the return pin 822 and the valve 604 inthe upward, closing direction. As soon as the actuator surface 846passes the lower margin of the cylinder cross drilling 832, additionalhigh pressure actuating fluid is available to generate the upwardclosing force on the actuator surface 846.

[0057] Damping action of the opening damping assembly 800 of FIG. 8occurs on the downward, open stroke of the valve 604. The initialportion of the opening stroke of the valve 604 is unopposed by actuatingfluid in either the return pin cylinder 828 or the damping chamber 830.CV2 502 is shifted to the vent disposition, dropping pressure in thereturn pin cylinder 828 and damping chamber 830 to ambient. The cylindercross drilling 832 is large enough such that the actuating fluid isforced out of the return pin cylinder 828 essentially withoutopposition.

[0058] Referring to frame B of FIG. 8, as soon as the actuator surface846 descends beneath the lower margin of the cylinder cross drilling832, the cylinder cross drilling 832 is sealed off by the return pin822. The damping action of the opening damping assembly 800 commences atthis point. Actuating fluid trapped in the lower portion of the returnpin cylinder 828 and the damping chamber 830 can only be expelled byforcing the actuator fluid around the damping ball 824 and through theorifice 852 defined at the ball stop 836. Increasing pressure in thedamping chamber 830 forces the damping ball 824 against the ball stop836 as depicted in frame B of FIG. 8. The resistance imposed on thereturn pin 822 by the pressure buildup in the damping chamber 830results in a slowing of the downward velocity of both the return pin 822and the valve 604, resulting in the reduction in the landing speed ofthe valve 604 as the valve 604 approaches its full open disposition.This damping is noted in FIG. 9 as the dashed line depicting openingdamping.

[0059] It will be obvious to those skilled in the art that otherembodiments in addition to the ones described herein are indicated to bewithin the scope and breadth of the present application. Accordingly,the applicant intends to be limited only by the claims appended hereto.

What is claimed is:
 1. A damping assembly for an engine valve, theengine valve being an intake/exhaust valve, the engine valveadmitting/exhausting a fluid mixture into/from a combustion chamber ofan internal combustion engine, comprising: damping apparatus having adamping chamber being selectively in fluid communication with a sourceof pressurized actuating fluid and being in fluid communication with anactuating fluid vent and being operably coupled to the engine valve, thechamber being floodable with a volume of actuating fluid, venting ofactuating fluid from the chamber being selectively restricted, therestriction imparting a force transmittable to the engine valve andacting to moderate engine valve landing speed during a closing stroke ofthe engine valve.
 2. The damping assembly of claim 1 wherein a controlvalve is operably, fluidly coupled to the chamber for selectivelyporting actuating fluid to the chamber and venting actuating fluid fromthe chamber.
 3. The damping assembly of claim 1 wherein the chamber isin fluid communication with a drive piston, the drive piston beingoperably coupled to the engine valve.
 4. The damping assembly of claim 3wherein the control valve is independently operably fluidly couplable toa drive piston drive surface.
 5. The damping assembly of claim 1, adamping ball being disposed in the chamber, a damping ball clearanceacting to restrict the venting flow of actuating fluid from the chamber.6. The damping assembly of claim 5 wherein at least a portion of theactuating fluid vented from the chamber transits the damping ballclearance under all operating conditions.
 7. The damping assembly ofclaim 5 wherein the damping ball is free to float in the chamber.
 8. Thedamping assembly of claim 3 wherein actuating fluid ported into thechamber generates a force on a damping ball hemisphere that istransmittable to the drive piston tending to translate the drive pistonin an opening stroke.
 9. The damping assembly of claim 1 wherein theengine valve has a known full closing stroke, the damping apparatusacting to moderate engine valve landing speed proximate the end of theclosing stroke.
 10. The damping assembly of claim 4 wherein drive pistontranslation acts to effect independent fluid coupling of the controlvalve to the drive surface.
 11. The damping assembly of claim 10 whereinventing of actuating fluid from the independent fluid coupling issubstantially unrestricted.
 12. The damping assembly of claim 10 whereinventing of actuating fluid is restricted to venting form the chamberonce the drive piston has sealed off the independent fluid coupling. 13.A damping assembly for an engine valve, the engine valve being anintake/exhaust valve, the engine valve admitting/exhausting a fluidmixture into/from a combustion chamber of an internal combustion engine,comprising: damping apparatus having a damping chamber being selectivelyin fluid communication with a source of pressurized actuating fluid andbeing in fluid communication with an actuating fluid vent and beingoperably coupled to the engine valve, the chamber being floodable with avolume of actuating fluid, venting of actuating fluid from the chamberbeing selectively restricted, the restriction imparting a forcetransmittable to the engine valve and acting to moderate engine valvelanding speed during a opening stroke of the engine valve.
 14. Thedamping assembly of claim 13 wherein a control valve is operably,fluidly coupled to the chamber for selectively porting actuating fluidto the chamber and venting actuating fluid from the chamber.
 15. Thedamping assembly of claim 13 wherein the chamber is in fluidcommunication with a return pin, the return pin being operably coupledto the engine valve.
 16. The damping assembly of claim 15 wherein thecontrol valve is independently operably fluidly couplable to a returnpin actuating surface.
 17. The damping assembly of claim 13, a dampingball being disposed in the chamber, a damping ball clearance acting torestrict the venting flow of actuating fluid from the chamber.
 18. Thedamping assembly of claim 17 wherein at least a portion of the actuatingfluid vented from the chamber transits the damping ball clearance underall operating conditions.
 19. The damping assembly of claim 17 whereinthe damping ball is free to float in the chamber.
 20. The dampingassembly of claim 16 wherein actuating fluid ported into the chambergenerates a force on a damping ball hemisphere that is transmittable tothe return pin tending to translate the return pin in a closing stroke.21. The damping assembly of claim 13 wherein the engine valve has aknown full opening stroke, the damping apparatus acting to moderateengine valve landing speed proximate the end of the opening stroke. 22.The damping assembly of claim 17 wherein return pin translation acts toeffect independent fluid coupling of the control valve to a return pinactuating surface.
 23. The damping assembly of claim 22 wherein ventingof actuating fluid from the independent fluid coupling is substantiallyunrestricted.
 24. The damping assembly of claim 22 wherein venting ofactuating fluid is restricted to venting from the chamber once thereturn pin has sealed off the independent fluid coupling.
 25. A dampingassembly for an engine valve, the engine valve being an intake/exhaustvalve, the engine valve admitting/exhausting a fluid mixture into/from acombustion chamber of an internal combustion engine, comprising: returndamping apparatus having a first damping chamber being selectively influid communication with a source of pressurized actuating fluid andbeing in fluid communication with a substantially ambient actuatingfluid vent and being operably coupled to the engine valve, the chamberbeing floodable with a volume of actuating fluid, venting of actuatingfluid from the chamber being selectively restricted, the restrictionimparting a force transmittable to the engine valve and acting tomoderate engine valve landing speed during a closing stroke of theengine valve: and opening damping apparatus having a second dampingchamber being selectively in fluid communication with a source ofpressurized actuating fluid and being in fluid communication with asubstantially ambient actuating fluid vent and being operably coupled tothe engine valve, the second chamber being floodable with a volume ofactuating fluid, venting of actuating fluid from the second chamberbeing selectively restricted, the restriction imparting a forcetransmittable to the engine valve and acting to moderate engine valvelanding speed during a opening stroke of the engine valve.
 26. Thedamping assembly of claim 25 wherein a control valve is operably,fluidly coupled to the first chamber for selectively porting actuatingfluid to the first chamber and venting actuating fluid from the firstchamber.
 27. The damping assembly of claim 25 wherein the first chamberis in fluid communication with a drive piston, the drive piston beingoperably coupled to the engine valve.
 28. The damping assembly of claim27 wherein the control valve is independently operably fluidly couplableto a drive piston drive surface.
 29. The damping assembly of claim 25, adamping ball being disposed in the first chamber, a damping ballclearance acting to restrict the venting flow of actuating fluid fromthe first chamber.
 30. The damping assembly of claim 29 wherein at leasta portion of the actuating fluid vented from the first chamber transitsthe damping ball clearance under all operating conditions.
 31. Thedamping assembly of claim 29 wherein the damping ball is free to floatin the first chamber.
 32. The damping assembly of claim 27 whereinactuating fluid ported into the first chamber generates a force on adamping ball hemisphere that is transmittable to the drive pistontending to translate the drive piston in an opening stroke.
 33. Thedamping assembly of claim 25 wherein the engine valve has a known fullclosing stroke, the damping apparatus acting to moderate engine valvelanding speed proximate the end of the closing stroke.
 34. The dampingassembly of claim 28 wherein drive piston translation acts to effectindependent fluid coupling of the control valve to the drive surface.35. The damping assembly of claim 34 wherein venting of actuating fluidfrom the independent fluid coupling is substantially unrestricted. 36.The damping assembly of claim 34 wherein venting of actuating fluid isrestricted to venting form the first chamber once the drive piston hassealed off the independent fluid coupling.
 37. The damping assembly ofclaim 36 wherein a control valve is operably, fluidly coupled to thesecond chamber for selectively porting actuating fluid to the secondchamber and venting actuating fluid from the second chamber.
 38. Thedamping assembly of claim 36 wherein the second chamber is in fluidcommunication with a return pin, the return pin being operably coupledto the engine valve.
 39. The damping assembly of claim 38 wherein thecontrol valve is independently operably fluidly couplable to a returnpin actuating surface.
 40. The damping assembly of claim 36, a seconddamping ball being disposed in the second chamber, a second damping ballclearance acting to restrict the venting flow of actuating fluid fromthe second chamber.
 41. The damping assembly of claim 40 wherein atleast a portion of the actuating fluid vented from the second chambertransits the second damping ball clearance under all operatingconditions.
 42. The damping assembly of claim 40 wherein the seconddamping ball is free to float in the second chamber.
 43. The dampingassembly of claim 39 wherein actuating fluid ported into the secondchamber generates a force on a second damping ball hemisphere that istransmittable to the return pin tending to translate the return pin inan closing stroke.
 44. The damping assembly of claim 25 wherein theengine valve has a known full opening stroke, the second dampingapparatus acting to moderate engine valve landing speed proximate theend of the opening stroke.
 45. The damping assembly of claim 28 whereinreturn pin translation acts to effect independent fluid coupling of thecontrol valve to a return pin actuating surface.
 46. The dampingassembly of claim 45 wherein venting of actuating fluid from theindependent fluid coupling is substantially unrestricted.
 47. Thedamping assembly of claim 45 wherein venting of actuating fluid issubstantially restricted to venting from the second chamber once thereturn pin has sealed off the independent fluid coupling.
 48. A methodof control for a valve, comprising: fluidly coupling a selectivelyactuatable controller with a source of pressurized actuating fluid andwith a substantially ambient actuating fluid reservoir; and controllingclosing landing speed of the valve by: a. operably coupling a chamber tothe valve; b. selectively independently porting actuating fluid to thechamber; and c. selectively restricting actuating venting actuatingfluid from the chamber, the restricting imparting a force to the valveacting to moderate valve closing landing speed.
 49. The method of claim48 including fluidly communicating the chamber with a drive piston andoperably coupling the drive piston to the valve.
 50. The method of claim48 including disposing a ball in the chamber, forming a damping ballclearance between the damping ball and a chamber wall, and restrictingthe venting flow from the chamber by means of the damping ballclearance.
 51. The method of claim 50 including venting at least aportion of the actuating fluid through the damping ball clearance underall operating conditions.
 52. The method of claim 50 includinggenerating a force on a damping ball hemisphere by actuating fluidported into the chamber, transmitting the force to the drive piston, andthereby driving the drive piston in an opening stroke.
 53. The method ofclaim 48, the valve having a known full closing stroke, includingmoderating valve closing speed proximate the end of the closing stroke.54. A method of control for a valve, comprising; fluidly coupling aselectively actuatable controller with a source of pressurized actuatingfluid and with a substantially ambient actuating fluid reservoir; andcontrolling closing landing speed of the valve by: a. operably couplinga chamber to the valve; b. selectively independently porting actuatingfluid to the chamber; and c. selectively restricting actuating ventingactuating fluid from the chamber, the restricting imparting a force tothe valve acting to moderate valve opening landing speed.
 55. The methodof claim 54 including fluidly communicating the chamber with a returnpin and operably coupling the return pin to the valve.
 56. The method ofclaim 54 including disposing a ball in the chamber, forming a dampingball clearance between the damping ball and a chamber wall, andrestricting the venting flow from the chamber by mean of the dampingball clearance.
 57. The method of claim 56 including venting at least aportion of the actuating fluid through the damping ball clearance underall operating conditions.
 58. The method of claim 56 includinggenerating a force on a damping ball hemisphere by actuating fluidported into the chamber, transmitting the force to the return pin, andthereby driving the return pin in an closing stroke.
 59. The method ofclaim 54, the valve having a known full opening stroke, includingmoderating valve closing speed proximate the end of the opening stroke.60. A method of control for a valve, comprising: fluidly coupling aselectively actuatable controller with a source of pressurized actuatingfluid and with a substantially ambient actuating fluid reservoir;controlling closing landing speed of the valve by: a. operably couplinga chamber to the valve; b. selectively independently porting actuatingfluid to the chamber; and c. selectively restricting actuating ventingactuating fluid from the chamber, the restricting imparting a force tothe valve acting to moderate valve closing landing speed; andcontrolling opening landing speed of the valve by: a. operably couplinga second chamber to the valve; b. selectively independently portingactuating fluid to the second chamber; and c. selectively restrictingactuating venting actuating fluid from the second chamber, therestricting imparting a force to the valve acting to moderate valveopening landing speed.
 61. The method of claim 60 including fluidlycommunicating the chamber with a drive piston and operably coupling thedrive piston to the valve.
 62. The method of claim 60 includingdisposing a ball in the chamber, forming a damping ball clearancebetween the damping ball and a chamber wall, and restricting the ventingflow from the chamber by mean of the damping ball clearance.
 63. Themethod of claim 61 including venting at least a portion of the actuatingfluid through the damping ball clearance under all operating conditions.64. The method of claim 62 including generating a force on a dampingball hemisphere by actuating fluid ported into the chamber, transmittingthe force to the drive piston, and thereby driving the drive piston inan opening stroke.
 65. The method of claim 60, the valve having a knownfull closing stroke, including moderating valve closing speed proximatethe end of the closing stroke.
 66. The method of claim 60 includingfluidly communicating the second chamber with a return pin and operablycoupling the return pin to the valve.
 67. The method of claim 60including disposing a ball in the second chamber, forming a damping ballclearance between the damping ball and a second chamber wall, andrestricting the venting flow from the second chamber by mean of thedamping ball clearance.
 68. The method of claim 67 including venting atleast a portion of the actuating fluid through the damping ballclearance under all operating conditions.
 69. The method of claim 67including generating a force on a damping ball hemisphere by actuatingfluid ported into the chamber, transmitting the force to the return pin,and thereby driving the return pin in an closing stroke.
 70. The methodof claim 60, the valve having a known full opening stroke, includingmoderating valve closing speed proximate the end of the opening stroke.